IOWA CITY, Iowa — After submitting to a second polygraph test, the mother of one of two missing Iowa cousins said Monday the results should prove that she had nothing to do with their disappearance and allow investigators to focus their attention elsewhere.

Misty Cook-Morrissey said a state agent asked during Monday's polygraph whether she had anything to do with the abduction of her daughter, 10-year-old Lyric Cook-Morrissey, and niece, 8-year-old Elizabeth Collins. She said she was asked whether she knows where they are and if she could take investigators to them, adding she answered "no" to all those questions.

"It went well," she said in a phone interview. "They can rule me out of their book and move on to something else."

The girls have been missing since they went for a bike ride July 13 in Evansdale, a town of 4,700 people in northeast Iowa, where their bikes and a purse were found near a lake. An extensive investigation involving local, state and federal agents has failed to find them. Investigators reclassified the case as an abduction after an FBI team used sonar equipment to search the bottom of the lake and ruled out the possibility that they drowned.

FBI spokeswoman Sandy Breault said Monday that investigators want to interview a person who was paddleboating on the lake around the time the girls disappeared. She said that person, who has not voluntarily come forward, could help investigators learn what happened to the girls but was not considered a suspect.

Black Hawk County Chief Deputy Rick Abben declined comment on Cook-Morrissey's polygraph test at a news briefing but said investigators were getting better cooperation from her and her husband than last week. He offered no other new information about the 11-day search, saying only that investigators continued to chase leads.

Abben also sounded less certain than an FBI spokeswoman did Saturday when asked whether investigators believe the girls are alive.

"We certainly would like to think that. We have nothing to indicate they are not," he said. "We want to keep hopes up."

Investigators have been delving into the background of Cook-Morrissey and her estranged husband, Dan Morrissey, who have both spent time in prison on methamphetamine-related charges. The two faced additional scrutiny last week when they announced they had been advised by an attorney to stop cooperating with investigators. A judge last week ordered Morrissey to be monitored by state parole agents while he awaits trial on charges of making and dealing meth that could lock him up for decades.

The couple's temporary lack of cooperation with police caused friction with Heather and Drew Collins, Elizabeth's parents. Abben had called it a distraction in recent days and called for total cooperation.

Cook-Morrissey said she'd declined to cooperate after she was treated harshly during a polygraph test last week in which she was accused of taking the girls, but agreed Monday after investigators promised to take a different approach and allow a relative to be nearby.

Cook-Morrissey, 34, said she was told she passed Monday's test after last week's came back inconclusive. She said the examinations were stressful for her since she has anxiety disorder, which made it hard to stay calm and may have contributed to the earlier inconclusive result.

Cook-Morrissey said Monday's test and a meeting afterward with investigators over doughnuts went a long way toward easing tensions between her family and the police.

"You could say we made peace today," she said. "We looked at some pictures. We talked. It went really well. I think they are trying a lot harder than I was feeling the last few days."

Cook-Morrissey said investigators did not share any new information with her about why they believe the girls are alive, but told her they were confident the case would be resolved.

She said she also met Monday morning with the Collins' family. She called tension within the family as "very normal" in a case where relatives have fear and stress but no answers about what happened.

A spokesman for the Collins' family, Craig Ceilly, emphasized that Heather and Drew Collins have been "cooperating 300 percent from day one" with investigators as they live through what he called their worst nightmare.

"Anything they can do to help they will do and they are doing willingly. I cannot speak for Dan and Misty," he said. "I don't know what they are doing. I don't have a clue, nor do Heather and Drew. They don't want to know. All of a sudden when the media started looking at their past, it took a turn for the worse."

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  • Lyric Cook, Elizabeth Collins

    This combo made from undated photos provided by the FBI shows cousins Lyric Cook, 10, right, and Elizabeth Collins, 8, who have been missing since Friday, July 13, 2012. Dan Morrissey, Lyric's father, is expected to learn Friday, July 27, whether he will be put on trial next week for domestic abuse or drug charges, raising the possibility that he could be sent to prison even as the search continues. (AP Photo/FBI)

  • Elizabeth Collins

    This photo provided by the FBI shows Elizabeth Collins, 8. Collins and her 10-year-old cousin Lyric Cook, who have been missing since Friday afternoon, July 13, 2012, when they went for a bike ride in Collins' neighborhood in Evansdale, Iowa. Their bikes were found a mile away near a lake, and investigators say they have no idea what happened to them. (AP Photo/FBI)

  • Lyric Cook

  • Elizabeth Collins, Lyric Cook-Morrissey

  • Misty and Dan Morrissey speak to the media near Meyers Lake where their daughter Lyric Cook-Morrissey, 10, and Elizabeth Collins, 8, disappeared last Friday, Tuesday, July 17, 2012, in Evansdale, Iowa. The girls' bikes were found Friday afternoon near a bike trail at the edge of the lake. (AP Photo/Charlie Neibergall)

  • Misty and Dan Morrissey walk to speak to the media near Meyers Lake where their daughter Lyric Cook-Morrissey, 10, and Elizabeth Collins, 8, disappeared last Friday, Tuesday, July 17, 2012, in Evansdale, Iowa. The girls' bikes were found Friday afternoon near a bike trail at the edge of the lake. (AP Photo/Charlie Neibergall)

  • Dan Morrissey leans on a tree near Meyers Lake where his daughter Lyric Cook-Morrissey, 10, and Elizabeth Collins, 8, disappeared last Friday, Tuesday, July 17, 2012, in Evansdale, Iowa. The girls' bikes were found Friday afternoon near a bike trail at the edge of the lake. (AP Photo/Charlie Neibergall)

  • Elizabeth Collins

    This undated photo provided by Black Hawk County police shows 8-year-old Elizabeth Collins, who, along with her 10-year-old cousin Lyric Cook-Morrissey, has been missing since Friday afternoon, July 13, 2012. The girls were last seen Friday afternoon leaving their grandmother's house. (AP Photo/Black Hawk County Police via Waterloo Courier)

  • This undated photo provided by Black Hawk County police shows 10-year-old Lyric Cook-Morrissey who, along with her 8-year-old cousin Elizabeth Collins, has been missing since Friday afternoon, July 13, 2012. The girls were last seen Friday afternoon leaving their grandmother's house. (AP Photo/Black Hawk County Police via Waterloo Courier)

  • Sarah Staebell ties pink ribbons for Cook-Morrissey and Collins. (AP Photo/Waterloo Courier, Brandon Pollock)

  • Police officers check a lower-level door of a business in Evansdale Monday, July 16, 2012 in the continuing search for Lyric Cook-Morrissey, 10, Elizabeth Collins, 8, who disappeared in Evansdale last Friday, July 13. (AP Photo/Waterloo Courier, Brandon Pollock)

  • An off-duty Cedar Rapids police officer searches the underbrush for clues to the disappearance of Lyric Cook-Morrissey and Elizabeth Collins along the bike trail around Meyers Lake in Evansdale Monday, July 16, 2012. The two girls have been missing since leaving their grandmother's house Friday afternoon. (AP Photo/Waterloo Courier, Brandon Pollock)

  • This photo provided by the FBI shows Elizabeth Collins, 8. Collins and her 10-year-old cousin Lyric Cook have been missing since Friday afternoon, July 13, 2012, when they went for a bike ride in Collins' neighborhood in Evansdale, Iowa. Their bikes were found a mile away near a lake, and investigators say they have no idea what happened to them. (AP Photo/FBI)

  • A poster with photos of Lyric Cook-Morrissey, 10, and Elizabeth Collins, 8, who disappeared in Evansdale last Friday, adorn a utility pole across from the entrance to Meyers Lake in Evansdale, Iowa, Monday, July 16, 2012. Their bikes were found Friday afternoon near a bike trail at the edge of Meyers Lake in Evansdale. (AP Photo/Waterloo Courier, Brandon Pollock)

  • Evansdale code enforcement officer Rick Reuter watches as Meyers Lake is drained while authorities continue to search for 10-year-old Lyric Cook-Morrissey and her cousin, eight-year-old Elizabeth Collins, who disappeared last Friday, July 13, 2012, in Evansdale, Iowa. (AP Photo/Waterloo Courier, Matthew Putney)